1. Field of the Invention
The present invention relates to running tools and wellbore components for use in a well. More particularly, the invention relates to a running tool for installing a wellbore component in a well. More particularly still, the invention relates to a flow-actuated release mechanism for a running tool.
2. Background of the Related Art
An oil or gas well includes a wellbore extending from the surface of the well to some depth therebelow. Typically, the wellbore is lined with a string of tubular like casing, to strengthen the sides of the borehole and isolate the interior of the casing from the earthen walls therearound. In the completion and operation of wells, downhole components are routinely inserted into the well and removed therefrom for a variety of purposes. For example, in some instances it is necessary to isolate an upper portion of the wellbore from a lower portion and a bridge plug can be inserted into the wellbore to seal the upper and lower areas from each other. In other instances, it is desirable to seal an annular area formed between two co-axial tubulars or between one tubular and an outer wall of the wellbore and a packer is typically inserted into the wellbore to accomplish this purpose.
In each instance, wellbore components are run into the wellbore on a tubular run-in string with a running tool disposed between the lower end of the tubular string and the wellbore component. Once the wellbore component is at a predetermined depth in the well, it is actuated by mechanical or hydraulic means in order to become anchored in place in the wellbore. Hydraulically actuated wellbore components require a source of pressurized fluid from the tubular string thereabove to either actuate slip members fixing the component in the wellbore or to inflate sealing elements to seal an area between the outside of the component and the inner wall of the wellbore therearound. Once actuated, the wellbore components are separated from the running tool, typically through the use of some temporary mechanical connection which is caused to fail by a certain mechanical or hydraulic force applied thereto. After the shearable connection has failed, the running tool and the tubular string can be removed from the wellbore leaving the actuated wellbore component therein.
Presently, more and more wellbore components are inserted into wells using a tubular string made up of coiled tubing. Coiled tubing, because it is light, flexible, compact and easily transported is popular for delivering wellbore components. For example, rather than assembling a tubular string with sequential joints of rigid pipe, coiled tubing can be delivered to the well site on a reel and simply unwound into the wellbore to the desired length. Additionally, when a wellbore component must be inserted into a live well, coiled tubing, with its constant outer diameter, is easier to use with pressure retaining components like stripers than sequential tubular sections having enlarged threaded connectors therebetween.
In spite of the advantages related to coiled tubing run-in strings for wellbore components, there are also disadvantages. For example, most wellbore components run into a well on coiled tubing are designed to be actuated with pressurized fluid delivered through the coiled tubing. Subsequently, these same components are designed to be disconnected from running tools by shearing a shearable connection between the running tool and the wellbore component. Coiled tubing, because it is relatively thin-walled, can expand in diameter when pressurized fluid is present in its interior. When setting a wellbore component, the pressurized fluid delivered through the coiled tubing adequate to set the component can also be adequate to expand the coiled tubing slightly resulting in a shortening of the coiled tubing string. This shortening can produce an upwards force which causes the shearable connection between the running tool and the component to fail, thereby disconnecting the running tool from the component before the component is completely set in the wellbore. There are other problems related to shearable connections between running tools and wellbore components that are present no matter what type of tubular run-in string is utilized. For example, a shearable connection which has been designed based upon faulty calculations can fail and dislodge the running tool from the wellbore component prematurely. Additionally, some shearable connections are designed whereby the shear pins are partially exposed to fluid pressure used to set the wellbore component. The result can be a shearable connection that fails prematurely.
There is a need therefore, for a wellbore component assembly which can be more easily inserted into a wellbore. There is a further need for a running tool for a wellbore component which does not rely upon physical force to become disconnected from the wellbore component. There is yet a further need for a running tool for a wellbore component having a detachment mechanism that is flow-actuated rather than actuated with physical force. There is yet a further need for a wellbore component assembly including a running tool which can be run into a well on a tubular string of coiled tubing. There is yet a further need for a running tool having a release mechanism that will not release prior to the setting of the wellbore component in the wellbore.
The invention provides a running tool for a wellbore component. In one aspect, the tool includes a body having a longitudinal bore therethrough with connection means at an upper end for connection to a tubular run-in string and a selective attachment assembly for a wellbore component therebelow. A flow directing member is disposed in the bore and is movable between a first and second position. At a predetermined flow rate through the member, the member moves to the second position and directs fluid towards the selective attachment assembly, thereby causing the running tool to become disengaged from the wellbore component after the wellbore component has been actuated and fixed in the wellbore.